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  1. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    person receiving the report won't under stand either term :D
  2. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    I have commented on the poor discrimination between devices and made them aware of the inconvenience a fault may cause . cheers lads thanks for your input ....
  3. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    Read the first post again it is not that confusing . The report will state that the 125a sub mains from the 400 amp panel board exceed maximum permissible zs values but the disconnection time will be met by the 80 amp switch fuse at source
  4. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    0.57 zs is on the outgoing sub mains from the 400 amp panel . sub mains are protected by 125 amp mccbs
  5. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    They are the same because they are next to one another
  6. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    not yet . Im going in early tomorrow so will test L N . The main panel and sub mains were installed 5 years ago with no paperwork and not a lot of thought in design . In your opinion does it warrant a code 2 ?
  7. jackhammerJIM

    Commercial sub mains exceed max zs of mccbs

    Thoughts required on todays scenario . Commercial premises fed from 100 amp 3 phase TNS supply ZE 0.40 feeds 80 amp 3 phase switch fuse (max zs 0.57) feeds 400 amp mainswitch protek panel in 35mm swa 16mm earth 125 amp mccb (0.24 max zs) submain exceeds max zs at 0.57 Had this down as a...
  8. jackhammerJIM

    Power Gain & Decibels Conversion Help.

    Ive got that wrong . Every 3db of gain requires a doubling of amplifier power .
  9. jackhammerJIM

    Power Gain & Decibels Conversion Help.

    A 3db increase in volume is percieved as twice as loud by the human brain .
  10. jackhammerJIM

    ... advice on this situation please

    I agree with this . No need to walk away , Explain you won't certify and take responsibility for work completed by other contractors . You could fit a new board large enough to accommodate a mains change whilst connecting only your circuits .
  11. jackhammerJIM

    Which shock would be worse?

    Theoretically speaking the current would be the same on line and neutral conductors ... Current is limited by the resistance
  12. jackhammerJIM

    Advice on going it alone

    If you have gone it alone ask the M&E firm if they will use you as a subcontractor ....
  13. jackhammerJIM

    Megaflo Y plan problem

    Over heat stat and 2 port valve are standard safety device on any unvented cylinder . Positive shut off can't be achieved with a 3 port valve hence the additional 2 port .
  14. jackhammerJIM

    Amps carried through air

    In dry conditions the human body alone can have a resistance of 100 000 ohms . However , during a sustained shock this resistance will drop rapidly . Ignoring the air 10 000/100000 = 0.1 amperes
  15. jackhammerJIM

    Flush mounted pull cord backbox and theories

    new build roof trusses are 600 mm
  16. jackhammerJIM

    Flush mounted pull cord backbox and theories

    I wouldn't fancy it in the middle of a 600 spacing

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